Kci Konecranes International Plc

Juhani Sirjola

Control system for rope bucket

The invention relates to a procedure and an apparatus for adjusting the speed of an induction machine (1) fed by a frequency converter or an inverter (2) to a value corresponding to a reference value (f.sub.R). In the procedure, a frequency signal (n.sub.m) depending on the actual speed of the motor is generated and the reference value (f.sub.R) Of the motor speed is corrected by means of a correction signal (C) proportional to the slip of the motor. The corrected reference value is used as a frequency reference (f.sub.S) for the frequency converter or inverter. According to the invention, the correction signal (C) proportional to the slip is generated with the aid of the frequency signal (n.sub.m) depending on the actual motor speed and another frequency signal (n.sub.s ') formed from the frequency reference (f.sub.s) of the inverter. When the motor speed changes, e.g. due to variation in the load, the reference frequency of the inverter is corrected correspondingly.

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Hyvinkaa, Finland

Juhani Sirjola